The effects of prestrain, strain rate, and temperature on the impact properties of 304L stainless steel are investigated using a compressive split-Hopkinson pressure bar. The impact tests are performed at strain rates ranging from 2000 to 6000 s−1 and temperatures of 300, 500, and 800 °C using 304L specimens with prestrains of 0.15 or 0.5. The results show that the flow stress, work-hardening rate, and strain rate sensitivity increase with increasing strain rate or decreasing temperature. As the prestrain increases, the flow stress and strain rate sensitivity increase, but the work-hardening rate decreases. The temperature sensitivity increases with an increasing strain rate, temperature, and prestrain. Overall, the effects of prestrain on the impact properties of the tested specimens dominate those of the strain rate or temperature, respectively. Finally, optical microscopy observations reveal that the specimens fracture primarily as the result of the formation of adiabatic shear bands.

Quasicrystals have been identified as alloys possessing unusually low surface energy. This results in poor adhesion properties of quasicrystalline coatings when deposited on metallic substrates, hindering the development of these new materials for technological applications. Here we investigate the possible use of complex Al-Cu metallic phases as interface layers to accommodate the structural and electronic mismatch between a quasicrystalline coating and a metallic substrate and improve adhesion. First, we show that all stable low-temperature phases of the Al-Cu system can be grown as thin films using DC magnetron sputtering. Among the various possible phases, we select the γ-brass γ-Al4Cu9 as a promising candidate for the interface layer. Then the γ-Al4Cu9 phase is grown on the fivefold surface of an icosahedral (i-) Al-Pd-Mn quasicrystal. The interface is investigated by transmission electron microscopy and shows a clear texturing of the film. The grains exhibit rotational epitaxy with the substrate. We find that the interface is mainly composed of a β-phase of unknown chemical composition and sometimes exhibits γ grains in direct contact with the quasicrystalline substrate. Occasionally, we observe a fourth phase at the β/γ interface, identified as β1, possessing a lattice parameter aβ1 equal to 2aβ and 2/3aγ.

In this study, the influence of T5 heat treatment on tensile and fatigue behavior of hot-extruded Mg–10Gd–3Y (wt%) magnesium alloy has been investigated. High cycle fatigue tests were carried out at a stress rate (R) of −1 and a frequency of 100 Hz using hour-glass-shaped round specimens with a gauge diameter of 5.8 mm. The results show that fatigue strength (at 107 cycles) of Mg–10Gd–3Y magnesium alloy increases from 150 to 165 MPa after T5 heat treatment, i.e., the improvement of 10% in fatigue strength has been achieved. However, the crack growth resistance is lowered by T5 heat treatment. Results of microstructure observation and scanning electron microscopy-energy dispersive x-ray (SEM-EDX) analysis suggest that the fatigue strength in the Mg–10Gd–3Y magnesium alloy is determined by the threshold stress of basal slip, which is induced by solid solution hardening and precipitation hardening.

An improvement of the fatigue resistance of rolled AZ31 magnesium alloy was attempted by reducing the tensile mean stress developed during fatigue deformation, which was achievable by tailoring the {10-12} twinning-detwinning characteristics of the material through the precompression process. The modification of the {10-12} twinning-detwinning characteristics made it possible to control the plastic deformation mechanisms activated during fatigue deformation so that the imposed tensile strain could be fully accommodated by detwinning alone, which led to a significant reduction of tensile flow stress, finally resulting in the reduction of mean stress.

Precipitation of ZrCu with the B2 structure in Zr50Cu50–xAlx (x = 0, 4, 6) metallic glasses by rapidly heating and cooling was investigated. By rapidly heating and cooling, the ZrCu B2 phase precipitates the most in Zr50Cu46Al4 metallic glass plates prepared by tilt-casting without using a silica nozzle. The amount of the ZrCu B2 phase precipitated in Zr50Cu46Al4 metallic glass ribbons prepared by using a silica nozzle decreases by Si diffused from the silica nozzle during the preparation. This work is discussed from the viewpoint of crystallization behavior and why larger Zr-based bulk metallic glasses can be formed by suction, tilt, and cap casting without using a silica nozzle.